Photoelectric weft-bobbin feeler for looms for monitoring the yarn stock on weft bobbins

ABSTRACT

The bobbin and/or shuttle are provided with light-responsive conditions such that two types of reflective light responses are created by a single-incident light beam. The two responses are received by two separate light detectors and a correctional signal is produced only if the two detectors simultaneously produce output signals.

United States Patent [51] im. Cl

[72] Inventors Erwin Llnlenboch; 003d 45/12 Jul-gen Erdmann, both 01Waldklrcla 1m [50] Field of Search 139/273 R, Brellpu, Germany 273 A,370; 250/219 R, 219 DF, 219 S [21] Appl. No. 33,114 [22] Filed Mar. 12,1970 References Cited [45] Patented Jan. 4, 1972 FOREIGN PATENTSAsslsnee 2 3am my 420,000 3/1967 Switzerland 139/273 A 9 [32] Pri ri yM". 1969 1,292,613 3/1962 France 139/273 A [33 1 Primary Examinerl-1enryS. Jaudon [31] P 19 12 9135 Attorney-Darbo, Robertson & Vandenburgh 54]PHOTOELECTRIC WEFFBOBBIN FEELER you #1 ACT: The bobbin and/or shuttleare provided with LOOMS FDR MONITQRING THE YARN g'g'acg light-responsiveconditions such that two types of reflective 0N WE" ROBBINS lightresponses are created by a single-incident light beam. 11 Claims, 3Drawing Figs. The two responses are received by two separate lightdetectors and a correctional signal is produced only if the twodetectors n 3 f simultaneously produce output signals.

PATENTEU JAN 4 B72 3.631.901 SHEET 1 BF 2 ERWW LANG'ENBAC JZ/RGENERDMANN IN V EN TOR5 SHEET 2 [IF 2 Fig. 3

R1 LANGENBACH I JUAGEN ERDMA NN v INVENTORS 5% &

PHOTOELECTRIC WEI'T-BOBBIN FEELER FOR LOOMS FOR MONITORING THE YARNSTOCK ON WEFT ROBBINS BACKGROUND AND SUMMARY OF THE INVENTION Thisinvention relates to improvements in a photoelectric weft bobbin feelerfor looms for monitoring the yarn stock on weft bobbins comprising:first means for scanning the surface of the weft bobbin by the use of ascanning light beam, second means for affecting said scanning light beammounted on said surface, said second means becoming exposed toreflections from said light beam when said yarn stock is drawn near theend, and third means for producing a first signal indicative of theapproximately empty" state of the bobbin responsive to said firstafi'ecting means being exposed.

In looms or automatic looms, it is necessary to monitor the yarn stockon the weft bobbin continuously during the weaving process. As soon asthe yarn stock on a weft bobbin approaches the end, a corrective signalis produced which either initiates the automatic change of the bobbin orstops the loom. Photoelectric weft-bobbin feelers have been provided tofulfill these requirements. There are substantially two types of suchphotoelectric weft-bobbin feelers:

In one type of photoelectric weft-bobbin feeler, light-modulatingdevices are affixed to the surface of the weft bobbin. These devicesbecome exposed as the yarn stock approaches the end. A light beamdirected to the surface of the weft bobbin impinges upon thelight-modulating device. The reflected modulated light beam falls on aphotoelectric detector and initiates appropriate operations such as thechange of bobbins or stopping of the loom. The light-modulating devicecan, for example, be a pattern of alternating colored rings comprisingcontrasting colors, one ring absorbing light and the next one reflectingit. Since the light is modulated, it will. produce analtemating-current-type electrical signal upon being received by thephotoelectric detector, which signal is used for the control of furtheroperations (see German Pat. No. 850,730).

A second type of photoelectric weft-bobbin feeler comprises a ring ofreflex-reflecting substance or layer on the surface of the weft bobbin.Again a light beam is directed to the weft bobbin. When the weft bobbinis approximately empty, nearly all of the incident light beam isreflected back into the direction of incidence or into a smallscattering angle thereabout. This reflected beam falls on aphotoelectric detector and initiates appropriate operations (see Germanspecifications 1,056,856 and 1,162,297 and US. Pat. No. 3,053,137).

The prior art photoelectric weft bobbin feelers mentioned above sufferfrom certain disadvantages.

When the shuttle with the weft bobbin is moved past the scanning lightbeam, a spurious light modulation can be effected by some other sequenceof light and dark spots, such as the light surface of the weft bobbinand dark yarn. In this case, the first-mentioned type of weft-bobbinfeeler will produce a false signal.

Furthermore, accidental reflexes can occur with the second-mentionedtype of wefi bobbin feelers such as reflexes from glossy spots of theloom or the shuttle or from the yarn material itself (for example in theweaving of brilliant silk), and these reflexes will cause false signals.

Therefore, it is an object of the invention to provide an improvedphotoelectric weft-bobbin feeler. Another object of the invention is toprovide a photoelectric weft-bobbin feeler which will not produce falsesignals due to causes other than the yarn on the bobbin being drawn nearthe end. A more specific object of the invention is to provide aphotoelectric, weft-bobbin feeler, in which neither unwanted light-beammodulation not due to modulating means on the bobbin nor spuriousreflexes will cause a corrective signal for initiating a change ofbobbin, stop of the loom or the like.

in accordance with the invention this is achieved by second means foraffecting a scanning light beam, mounted on the said second affectingmeans being also scanned by a scanning light beam at the same time asthe said first affecting means, second signal-producing means forproducing a second signal indicative of the moment or period of time inwhich the bobbin is to be scanned and means for initiating controloperations responsive to said first and second signals from said firstand second signal-producing means. To put it another way: a light beamis directed toward the bobbin which beam is divided into two components.One component is coded to indicate whether or not the bobbin isapproximately empty. The second component is coded in a different mannerto signify the proper time for reading the first component. The codingcan be by pulsing the beam or by the position of the component whenreflected.

The particular advantages achieved'by the invention are that accidentalreflexes similar to those occurring during the scanning of the emptybobbin surface cannot cause false correction signals, as reflex signalsbecome effective only in conjunction with a signal indicating that thebobbin surface is being scanned.

In one embodiment of the invention, said scanning means are adapted toproduce one single light beam for scanning both said light-affectingmeans, and said affecting means are adapted to afl'ect said light beamin different ways so as to produce two signals discernible from eachother.

Thus, the required optical apparatus is not much more than in the priorart devices, i.e., only one scanning light beam is required. This singlelight beam can, for example, be modulated in difi'erent ways by the twoafi'ecting means. The modulated output signals from a singlephotoelectric detector, on which the modulated scanning light beamfalls, can be separated by appropriate electronic circuits.

Also, the signals can be separated optically. This is done in anembodiment of the invention, wherein said single scanning light beam isdirected to said two afi'ecting means at an acute angle, the firstaffecting means being adapted to regularly reflect said light beam to afirst photoelectric detector, the second affecting means being adaptedto reflect said light beam back into its direction of incidence to asecond photoelectric detector. The output signals of said first andsecond detectors are then applied to an AN D-gate to produce acorrection signal when they coincide. This embodiment of the inventionoffers the particular advantage that the separation of the two signalsis effected in simple manner by making use of optical laws; theadditional apparatus, as compared to the prior art, being little morethan one additional photoelectric detector.

A specific embodiment of the invention is a photoelectric weft-bobbinfeeler, wherein the surface of the bobbin (mounted in the shuttle) isscanned by the incident light beam through an elongated aperture in theshuttle, wherein below said aperture specularly reflecting andlight-absorbing rings are provided on the surface of the bobbin andalternating in fore-and-aft direction thereof, and wherein areflex-reflector is attached to the shuttle adjacent and along saidaperture, the scanning light beam having elongated cross section to scanover the rings and the reflex-reflector at the same time. Thereby asimple arrangement is obtained which can be used easily in conventionallooms. Further advantages are achieved, by using alternating reflectingand light-absorbing rings. Thereby the scanning light beam is modulatedand the photoelectric detector produces an altemating-current (AC)- typesignal. This signal is fed to a dynamic AC amplifier, whereby all falseactuations resulting from yarn reflexes will be eliminated.

An AC signal that can be evaluated reliably will be produced even by onereflecting and one adjacent light-absorbing ring. In this case, the ACsignal" occurring during the scanning will be a step signal caused bythe line of contrast between the rings.

When reflecting yarn is being processed on a loom, the contrast step canbe obtained by making the bobbin surface dark,

weft bobbin or on elements (shuttle) receiving said bobbin, i.e.,light-absorbing. When a portion of the last layer of yarn has been drawnfrom the bobbin, the contrast step occurs when the beam scans from thebobbin surface to the remaining yarn. The same situation will occur ifdark yarn is to be processed and the bobbin surface has been madereflecting.

DESCRIPTION OF DRAWINGS FIG. 1 schematically illustrates a portion of ashuttle, the weft bobbin and the photoelectric feeler at the moment ofthe scanning of the bobbin and shuttle;

FIG. 2 shows a portion of the shuttle and the aperture through which thebobbin is viewed; and

FIG. 3 is a block diagram of the electronic evaluation circuit.

DESCRIPTION OF SPECIFIC EMBODIMENTS The following disclosure is ofl'eredfor public dissemination in return for the grant of a patent. Althoughit is detailed to ensure adequacy and aid understanding, this is notintended to prejudice that purpose of a patent which is to cover eachnew inventive concept therein no matter how others may later disguise itby variations in form or additions or further improvements. The claimsat the end hereof are intended as the chief aid toward this purpose, asit is these that meet the requirements of pointing out the parts,improvements, or combinations in which the inventive concepts are found.

Referring to FIG. 1, reference numeral 1 designates the photoelectronicfeeler device. A light beam, emitted from light source 2, .is collimatedby a lens 3. It then is directed through partially transparent(beam-splitting) mirror 4 to the weft bobbin 9 and a reflex-reflector13. The light beam reflected by the reflex-reflector 13 back along itspath of incidence is deflected by the partially transparent mirror 4.The deflected portion reaches photoelectric detector 6 through lens 5.Another portion of the light beam passes through aperture 12 (at oneside of the reflex-reflector 13). This portion strikes the weft bobbin9. This portion of the light beam is specularly reflected from thesurface of the weft bobbin (when there is no more yarn on the bobbin)and reaches photoelectric detector 8 through a lens 7.

Reference numeral 11 designates the wall of the shuttle in which theweft bobbin 9 is mounted. It has the aperture 12 through which a portionof the light beam gets to the weft bobbin 9. Reference numeraldesignates a thread wound on the weft bobbin. When the yarn stock on thebobbin 9 approaches the end, black and white varnished rings 14 and 15,respectively, become visible to the incident beam. By the sequence of alight-absorbing and specularly reflecting ring, the scanning light beamwill detect the contrast step (when the yarn stock on the bobbin is ator approaching the end). The portion of the beam reflected to detector 8will be pulsed to pulse the electrical output of the detector.

FIG. 2 illustrates, how the reflex-reflector 13 is positioned on theshuttle wall adjacent the aperture 12. The weft bobbin would be behindthis aperture 12. The light beam 16 has an elongated cross section, asshown in dotted lines. This elongation is transverse to the direction ofmovement of the shuttle so that the reflex-reflector I3 and the surfaceof the weft bobbin are scanned simultaneously.

FIG. 3 illustrates, in principle, how the output signals from the twodetectors 6 and 8 are evaluated. The output signals are applied to anAND-gate 19 through two amplifiers l7 and 18. The output signal of theAND-gate is a correction signal to control (in a well-known manner notshown) further operations. For example, this correction signal initiatesthe automatic change of the bobbin. The correction signal from theAND-gate is produced only from detectors 6 and 8 if both signals arepresent. The amplifier 18 produces an output signal to the AND-gate onlyif the input signal from the photoelectric detector 8 is of thealternating current type, i.e., it amplifies only AC signals or stepsignals.

The reflex-reflector 13 shown in FIG. 2 may be a layershaped,reflex-reflecting substance or a strip on which a plurality of smalltriple reflectors are arranged closely side-byside.

We claim:

I. In the process of detecting and actuating a corrective signal inresponse to an approximately empty situation of a bobbin member carriedby a shuttle member of a loom wherein said situation is detected by agiven condition of said bobbin member being present, the improvementcomprising the steps of:

checking to determine if a particular condition of one of said membersis present;

at the same time making said check for said given condition;

and

initiating said corrective signal only when said conditions existsimultaneously.

2. In the process of claim I, wherein a light beam is directed towardssaid bobbin member;

said light beam is divided into two components;

one of said components being coded in a predetermined fashion if saidsituation is present; and

said other component being coded in another fashion in response to saidparticular condition being present.

3. In an apparatus for detecting and initiating a corrective signal inresponse to an approximately empty situation of a bobbin member carriedby a shuttle member of a loom wherein a first means senses a givencondition of said bobbin member as indicative of said situation toproduce a first output signal, the improvement comprising:

second means for checking one of said members for the existence of aparticular condition at each instant and for producing a second outputsignal when said particular condition exists on the one member; and

third means connected to the first two means to initiate said correctivesignals upon the simultaneous occurrence of the first and second outputsignals.

4. In an apparatus as set forth in claim 3, wherein said first andsecond means include a common device for producing a single light beamdirected at said members and separate respective light detectors, saidconditions affecting said light beam in different ways to produce twoseparate reflective light responses, said detectors being positioned toreceive said light responses respectively.

5. In an apparatus as set forth in claim 4, wherein said conditions area single identical condition which simultaneously produces said twoseparate reflective light responses.

6. In an apparatus as set forth in claim 4, wherein said single lightbeam is directed at said conditions at an acute angle, said givencondition reflecting said light beam to the detector of the first means,said second means including a partially reflective mirror in the path ofthe single light beam, said particular condiu'on including reflectivemeans for reflecting some light from said single beam back into itsdirection of incidence to said mirror and the detector of the secondmeans, said third means including an AND-gate.

7. In an apparatus as set forth in claim 6, wherein said shuttle memberhas an elongated aperture through which the bobbin member is viewed bysaid single light beam and a reflex reflector at one side of saidaperture, and the portion of said bobbin member so viewed by said lightbeam has light-reflecting and light-absorbing rings alternating in thefore-and-aft direction thereof.

8. In an apparatus as set forth in claim 7, wherein the detector of thefirst means produces an alternating-current-type electric signal, andsaid first means includes an amplifier which will amplify onlyaltemating-current-type signals.

9. In an apparatus as set forth in claim 7, wherein said rings are whiteand black varnished rings.

I0. In an apparatus as set forth in claim 3 for use with alight-reflective yarn, wherein the bobbin member has a lightabsorbingsurface.

11. In an apparatus as set forth in claim 3 for use with alight-absorbing yarn, wherein the bobbin member has a lightreflectivesurface.

1. In the process of detecting and actuating a corrective signal inresponse to an approximately empty situation of a bobbin member carriedby a shuttle member of a loom wherein said situation is detected by agiven condition of said bobbin member being present, the improvementcomprising the steps of: checking to determine if a particular conditionof one of said members is present; at the same time making said checkfor said given condition; and initiating said corrective signal onlywhen said conditions exist simultaneously.
 2. In the process of claim 1,wherein a light beam is directed towards said bobbin member; said lightbeam is divided into two components; one of said components being codedin a predetermined fashion if said situation is present; and said othercomponent being coded in another fashion in response to said particularcondition being present.
 3. In an apparatus for detecting and initiatinga corrective signal in response to an approximately empty situation of abobbin member carried by a shuttle member of a loom wherein a firstmeans senses a given condition of said bobbin member as indicative ofsaid situation to produce a first output signal, the improvementcomprising: second means for checking one of said members for theexistence of a particular condition at each instant and for producing asecond output signal when said particular condition exists on the onemember; and third means connected to the first two means to initiatesaid corrective signals upon the simultaneous occurrence of the firstand second output signals.
 4. In an apparatus as set forth in claim 3,wherein said first and second means include a common device forproducing a single light beam directed at said members and separaterespective light detectors, said conditions affecting said light beam indifferent ways to produce two separate reflective light responses, saiddetectors being positioned to receive said light responses respectively.5. In an apparatus as set forth in claim 4, wherein said conditions area single identical condition which simultaneously produces said twoseparate reflective light responses.
 6. In an apparatus as set forth inclaim 4, wherein said single light beam is directed at said conditionsat an acute angle, said given condition reflecting said light beam tothe detector of the first means, said second means including a partiallyreflective mirror in the path of the single light beam, said particularcondition including reflective means for reflecting some light from saidsingle beam back into its direction of incidence to said mirror and thedetector of the second means, said third means including an AND-gate. 7.In an apparatus As set forth in claim 6, wherein said shuttle member hasan elongated aperture through which the bobbin member is viewed by saidsingle light beam and a reflex reflector at one side of said aperture,and the portion of said bobbin member so viewed by said light beam haslight-reflecting and light-absorbing rings alternating in thefore-and-aft direction thereof.
 8. In an apparatus as set forth in claim7, wherein the detector of the first means produces analternating-current-type electric signal, and said first means includesan amplifier which will amplify only alternating-current-type signals.9. In an apparatus as set forth in claim 7, wherein said rings are whiteand black varnished rings.
 10. In an apparatus as set forth in claim 3for use with a light-reflective yarn, wherein the bobbin member has alight-absorbing surface.
 11. In an apparatus as set forth in claim 3 foruse with a light-absorbing yarn, wherein the bobbin member has alight-reflective surface.